1. Field of the Invention
The present invention is related to a transmission box, and more particularly, to a transmission box structure carrying a plurality of reticle pods, the structure of which and of AMHS are used for transferring the plurality of reticle pods.
2. Description of the Prior Art
Optical lithography tool plays an important role in the rapidly developing modern semiconductor technology. The pattern definition relies fully on optical lithography technology. In the application of optical lithography tool related to semiconductors, pre-designed circuit paths are fabricated into light-transparent reticles in specific forms. According to the principle of exposure, after light emitted from the light source passes through the reticle and is projected on a silicon wafer, specific circuit pattern can be exposed on the silicon wafer. However, since any kind of dust (such as particles, powders, and organic matters) that adheres to the reticle can result in quality degradation of projected pattern, the reticle used to produce pattern on silicon wafers is required to be kept absolutely clean. Therefore, a cleanroom environment is usually provided in ordinary wafer fabrication processes to prevent from contamination caused by particles in the air.
In semiconductor process, as the wafer size has progressed to the current 12″ and is still increasing, wafer foundries have set up considerably high standards for automation. By employing computer-integrated manufacturing systems and AMHS, wafer foundries will be able to automatize 100% of its wafer transferring process and also greatly reduce errors caused by manual operation, increase product yield, and streamline factory management.
FIG. 9 is a view of a reticle pod already in use in semiconductor FAB; the reticle pod comprises: a bottom base a, an upper cover b opposite to the bottom base a, and a supporting piece c located on the bottom base a, wherein the supporting piece c supports a reticle d and the reticle d is enclosed within by the bottom base a and the upper cover b.
In a typical reticle transferring process, the reticle is placed in a reticle pod, which is a box in airtight status; therefore, the reticle can be protected from contamination of dust particles when it is placed in the reticle pod. Reticle pods are usually transferred manually by operators, who, for example, place a plurality of reticle pods on a cart and the reticle pods on the cart are transferred for the next stage of the process to be performed. However, in current process, the size of reticle has been continually increasing and its weight has also been increasing, and in manual handling and transferring processes, it is inevitable that reticle pods may sometimes drop and serious loss of cost may be caused. Moreover, when the wafer size has progressed to 12″ or beyond, the whole wafer foundry may need to adopt automated systems for its production, and the transferring and handling of reticle pods should also be automatized to catch up with the trend; for example, a safest and fastest way to transfer a reticle pod is using a robot to handle it.
In view of the concerns mentioned above and to further prevent reticle pods from dropping when being transferred and to fulfill future requirements of wafer foundries for AMHS, provision of a transmission box which is able to safely and efficiently transfer a plurality of reticle pods is thus necessary.